Pipe-threading machine



{ No Model.) 4Sheets-Sheet 1'.

- L. B. CURTIS.

PIPE THREADING MACHINE. No. 509,878. Patented Dec. 5, 1893.

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PIPE THREADING MACHINE.

N0. 509,878. Patented Dec. 5. 1893.

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v L. CURTIS. I PIPE THREADING MAUHINEL No. 509,878. PatentedDeo. 5,1893.

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L. B. CURTIS,

-PIPE THRBADING MACHINE.

No; 509,878. Patented Dec. 5, 1893.

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bodying my invention.

UNITED STATES PATENT ()rFIoEa LEWIS B. CURTIS, CF SOUTHPORT, ASSIGNOR TOCURTIS & CURTIS, CF BRIDGEPORT, CONNECTICUT.

PIPE-TH READING MACHINE.

SPECIFICATION forming part of Letters Patent No. 509,878, dated December5, 1893.

Application filed March 16,1893- Serial No. 466,314. (No model.)

use the same.

My invention relates to certain new and useful improvements in pipethreading machines, but particularly has reference to that class of suchmachines in which a single pointed thread cutting tool is used.

Heretofore, in order to cut a thread on a taper, it has been necessaryfor the operator to advance and retract the tool manually during itslengthwise travel along the pipe, but

the inaccuracies attaching to this method are such that it is generallyconsidered impracticable, and machines of this class are used in veryrare instances, and then only for the purpose of cutting straightthreads.

The object of my present invention is to render the action of thecutting tool automatic as to its adjustment to the taper required, sothat as said tool is revolved it will automatically cut the threads to agiven taper.

In the accompanying drawingsFigures 1, 3 and 5, are front elevations ofmachines em- Figs. 2, 4 and 6, are sectional elevations respectively ofthe constructions shown in Figs. 1, 3 and 5, and Fig. 7, is a sectionalelevation showing still another way of carrying out my invention.

Similar numbers denote like parts in the several figures of thedrawings.

In Figs. 1 to 6 inclusive, the cutting tool is caused to advance andretreat by means of suitable inclines, while in Fig. 7, these movementsof the tool are efiected bya screw.

Referring to all the figures; 1 is a casing, 2 a vise in said casing forholding the pipe, 3 the vise operating screw, t a threaded hub extendingfrom said casing and constituting a lead screw, 5 a lead nut engagingsaid lead screw, and 6 a handle projecting from said lead nut wherebythe latter may be revolved.

Referring to Figs. 1 and 2', it will be seen that the lead screw isthreaded on a taper as at 7, while the lead nut is open at the bottom soas to have the quality of expanding and contracting, said nut being alsothreaded on a taper as at 8, to engage the threaded tapered portion ofthe lead screw. 9 is the cutting tool adapted to slide Within ways inthe forward part of the lead nut, and 10 is an ordinary thumb screwworking through an extensionlll from the handle 6 and swiveled at itslower end to said tool, the obvious pur pose of this screw-being toprovide means for normally adjusting the tool. 12 denotes the pipe to bethreaded. The tool is adjusted so that at first it will cut the taperedthread only for a short distance on the pipe, then, after running thetool back to its first position it is adjusted a little farther inward,so that in the next operation it will out said thread deeper andthroughout a longer distance on the pipe, and so on, each successivecutting of the tool being deeper (that is, nearer the axis of the pipe)and longer. During theinward travel of the tool, the axis of the leadnut will progressively move away from the axis of the pipe owing to theresistance offered to the tool by the pipe thereby gradually andconstantly retracting the cutting tool and causing the same to cut thethreads on a tapered area which is concentric with'the tapered area ofthe lead screw.

In Figs. 3 and 4, a wedge 13 is shown supported in the lead nuttransversely thereof and having a coil spring 14 around the same andbearing against the handle 6 and a pin 15, extending from said wedge,the function of said spring being to hold the rear end of the wedgeagainst the casing at all times. The cutting tool is adapted to slide inways in the front part of the lead nut and is recessed at 16. The upperpart of the tool is formed into a yoke 17 which surrounds the wedge, anda thumb screwlS is passed up through a cross-piece 19 of the toolagainst the incline 20 of the wedgeby means of which screw the normaladjustment of the tool is effected. The threads on the lead screw andlead nut are straight, as seen at 7, 8 and not tapered, and as the nutadvances, the spring 14 will be compressed and the cutting tool willalso advance along the wedge, and will gradually be retracted as the setscrew 18 travels up the incline 20. Owing to the resistance offered tothe tool by the pipe, the screw will always be kept firmly against theincline during operation, and by reason-of a coil spring 21 placedbetween the upper edge of the wedge and the inner wall of the yoke 17,the Screw will be kept against the incline when the tool is beyond theend of the pipe.

In Figs. 5 and 6, the lead screw and lead nut have straight and nottapered threads, but from the end of said screw extends a plain taperedpart 22 which is engaged by the inclined gate 23 in the tool carriage 24which latter is guided in the lead nut so as to be capable of afreesliding movement in a plane at right angles to the axis of the pipe. Thecutting tool 9 is guided Within the carriage 24 and is swiveled to thethumb screw 10 as in Fig. 2. As the cutting tool travels along the pipe,said tool will gradually be retracted therefrom, and during the retreatof the tool toward the end of the pipe said tool will be advanced towardthe pipe.

In the construction shown at Fig. '7, the threaded portions of the leadscrew and nut are straight, and two ears 25, 26, extend forward from thenut, between which cars is journaled a threaded shaft 27 confined asagainst any movement but revolution. 28 is a horizontal shaft journaledin the body of the lead nut and having splined on its rear end a spurgear 29 while on the front end is secured a bevel gear 30. The spur 29is in engagement with gear teeth 31 sunk in the circumference of thecasing l, and the shaft 28 is free to slide through said spur, so thatit will be readily understood that when the lead nut is revolved, saidspur will also be revolved and will impart revolution to the shaft 28during the advance of the lead nut. The bevel gear 30 is in engagementwith the bevel gear 32 secured on the shaft 27, whereby the latter isrevolved.

The cutting tool 9 is capable of vertical reciprocation within theforward part of the lead nut and has its adjusting thumb screw 10 passedthrough the nut 83, which latter is operatively mounted 011 the threadedpart of the shaft 27, said nut acting as a carriage for the cuttingtool.

The relation of the gears to each other and the pitch of the threads onthe shaft 27 are predetermined, so that the cutting tool will, duringthe inward and outward travel of the lead nut, be retracted from andadvanced toward the axis of the pipe, thereby conforming in its field ofaction to the required taper.

From the foregoing it will be evident that there are many ways in whichI can carry out my invention,and I do not therefore wish to be limitedto any particular construction of holding the object to be threaded, apermanent stationary lead screw and a permanent lead nut in operativeengagement therewith, and in combining with these parts a single pointedcutting tool carried by said lead nut and moving in harmony therewithbut having also an independent movement in a plane at right angles tothe axis of the object to be threaded.

I claim- 1. In amachine for cutting tapered screw threads onacylindrical surface, the combination of a stationary vise for holdingthe object to be threaded, a permanent stationary lead screw independentof the latter, a permanent lead nut in operative engagement with saidscrew, a single pointed cutting tool carried by said lead nut and movingin harmony therewith but capable of an independent movement in a planeat right angles to the axis of the object to be threaded, and means forautomatically efiec'ting such independent movement during the travel ofthe lead nut, substantially as set forth.

2. In a pipe threading machine, the combination of a stationary pipeholding vise, a permanent stationary lead screw, a permanent lead nutengaging said screw, a single pointed cutting tool carried by said notand moving in harmony therewith but capable of an independent movementin a plane at right angles to the axis of the pipe, and means operatedthrough suitable'inclines for automatically efiecting the independentmovements of said tool, substantially as set forth.

3. In a pipe threading machine of the character described, thecombination of the casing, the pipe holding vise therein, the lead screwhaving a plain tapered part extending therefrom, the lead nut, the toolcarriage guided within said nut and capable of a vertical play andhaving an inclined gate in engagement with said tapered part, and thesingle pointed cutting tool mounted in said carriage, substantially asset forth.

4. In a pipe threading machine the combination of stationary means forholding the pipe, a single pointed cutting tool, means independent ofsaid pipe for supporting, revolving and leading said tool bodily alongand around the pipe, and means independent of such pipe forautomatically imparting to said tool during such revolution and leadinga constant movement in a plane at right angles to the axis of the pipe,substantially as set forth.

In testimony whereof I affix my signature in presence of two witnesses.

LEWIS B. CURTIS.

Witnesses:

F. W. SMITH, Jr., A. S. MELOY.

